Adjustable orifice for use in differential pressure apparatus



Aug. 13, 1963 w. A. KATES 3,100,620

ADJUSTABLE ORIFICE FOR USE IN DIFFERENTIAL PRESSURE APPARATUS Filed Aug. 3, 1960 INVENTOR.

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United States Patent 3,100,620 ADJUSTABLE ORIFICE FOR USE IN DIFFEREN- TIAL PRESSURE APPARATUS Willard A. Kates, Deer-field, 111., assignor to The W. A. Kates Company, a corporation of Illinois Filed Aug. 3,1960, Ser. No. 47,327 5 Claims. (Cl. 251-208) This invention relates to a differential pressure responsive system and more particularly to apparatus providing a pressure diiferenn'al creating orifice particularly adapted for use in such systems.

This application comprises a continuation-impart of my copending application Serial No. 742,225, filed June 16, 1958, for a differential pressure system.

It is a general object of the present invention to produce a new and improved apparatus for use in pressure differential responsive systems.

It is a more specific object of the present invention to produce an improved adjustable orifice which may be utilized to create the pressure differential in systems of the type described in the preceding paragraph.

It is still another object of the invention to produce an 3,100,620 Patented Aug. 13, 1963 Ice valve cylinder 127 by suitable means such as a screw '128. Axially slidable within thelower portion of the valve cylinder is a cup-shaped valve piston 129 having a frustoconical upper end 130 controlling an opening 131 communicating between annular chamber 120 and a chamber .132 defined by the orifice cylinder, the valve cylinder, and the valve piston. The valve piston is biased downwardly by a coil spring 133, the downward movement of the piston being limited by a retainer 134 extending across the lower end of the valve cylinder 127. Balancing of the flow regulating valve is effected by means of fluid pressure in a lower chamber 135 in which the lower half of the valve cylinder 127 and the valve piston 1.29 are disposed, the chamber 135 having communication with inlet passage 118 through an interconnecting passage 136. A drain plug 137 is provided for controlledly closing" a drain opening 138 in the bottom portion of the body 112 leading from chamber-135. The valve cylinder is sealed to the body 112 by means of an O-ring 139 intermediate the chambers 1-2-0 and 135.

Adjustable orifice assembly 122 includes a pair of annul-ar orifice cylinders 140 and 141 coaxia lly rotatable improved adjustable orifice forming device of the character described wherein the orifice may take the form of an elongated slot, the length of which is adjustable, thereby to adjust the effective area of the orifice.

A further object of the invention is to provide an adjustable orifice forming device of the character described wherein orifices having extremely narrow widths may be provided with high accuracy. r

g It is a further object of the invention to provide such an adjustable orifice forming device having such high width accuracy which is extremely simple and economical of construction.

. Other and further objects and advantages of the inven tion will be apparent from the following description and drawings, in which:

FIGURE 1 is a vertical section through an apparatus embodying the invention; and

FIG. 2 is a fragmentary transverse section. taken substantially along the line 22 of FIG. 1.

While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail a single embodiment, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

As shown in the drawing, the invention comprehends apparatus generally designated 110, including a casing generally designated 111, defined by a lower body 112, and an upper bonnet 113 secured to the body by suitable means suchv as bolts 114 to define therebetween a chamber 115 sealed by means of an annular O-ring 116 disposed concentric of the chamber between the body and bonnet. The body is provided with an inlet 117 communicating with chamber 115 by means of a passage 118, and is further provided with an outlet 119 communicating with an internal annular chamber 120 by means of a passage 121. A pressure differential is provided between the inlet 117 and the outlet 119' by means of an adjustable orifice assembly generally designated 122 disposed in chamber 115, and a flow regulating valve 123 associated with the adjustable orifice assembly for regulating the flow from the adjustable orifice assembly 122 and chamber 120. Orifice assembly 122 may be adjusted by a manually operable means generally designated 124 to provide an accurately regulated pressure differential.

More specifically, the flow regulating valve 123 includes an orifice cylinder 125 secured to a flange '126 of a tubular on a cylindrical boss 142 upstanding from orifice cylinder 125. The boss 142 is provided with the downwardly opening axial recess 143 communicating at its lower end with chamber 132 and communicating :at its upper end with chamber 115 through an arcuate slot 144 extending through the wall of the boss approximately 160 about the axial recess 143.

The orifice cylinders 140 and 141 are spaced axially by an arcuate shim 145 extending approximately 200 around the boss 142 at the horizontal plane of the midportion of the slot 144. The orifice cylinder 141 is secured to the lower orifice cylinder with shim 145 thusly disposed therebetween by suitable means such as screw 146, thereby arranging the orifice cylinders to de fine an arcuate slit 147 extending approximately 160 around the boss 142 between the opposite ends of the shim 145. The lower orifice cylinder 140 bears downwardly against the upper surface 148 of orifice cylinder 125 and the axial length thereof is preselected to dispose the slit 147 at approximately the horizontal central plane of slot 144. The lower surface 149 of the upper orifice cylinder 141 and the upper surface 150 of the lower orifice cylin der 140 are preferably made highly accurately planar, as by lapping, and the shim 145 is preferably formed of shim stock having a highly accurate preselected thickness, so that the width of the slit 147 may be controlled with a high degree of accuracy, including where the width is of extremely small magnitude, such as approximately .001 inch.

Adjustment of the rotational position of the adjustment orifice assembly 122 is elfected by the adjustment means 124 which includes a manually operable knob 151 secured to a shaft 152 by suitable means'such as set screw 153. A plate 154 may be secured to the top of bonnet 113 for cooperation with a dial 155 secured to the knob 151 by a clamp ring 156 and a clamp screw 157 to indicate the condition of the valve.

Shaft 152 is mounted for free rotation in bonnet 113 by means of a ball thrust bearing 158 retained in association with the bonnet by a retainer 159 secured to the bonnet by a retainer clamp screw 160. A pair of O-n'ngs 161 is provided in the lower portion of the shaft for sealingthe shaft rotatively to the bonnet. The lower end of the shaft is provided with an enlargement 162 connected to the upper orifice cylinder 141 for transmitting rotation thereto whereby the rotational position of the slit 147 is adjusted relative to the slot 144 to control the effective area of the flow passage between chamber 115 and recess 143 with an extremely high degree of accuracy.

The flow regulator apparatus 110 accurately controls From recess 143 the fluid may pass through chamber '132 and outwardly through opening 131 and annular chamber 120 to the outlet 119, as regulated by the valve member end 130. The effective area of the flow passage defined by slit 147 and slot 144 is accurately controlled by the manipulation of handle 151 to provide an accurate control'of'the flow provided by apparatus 116 including at very small fluid flow rates. a I

- In many installations where an orifice is used to create a pressure differential, which differential is utilized to measure or regulate flow, it is necessary to have straight clear runs of to 30 diameters of pipe upstream and downstream from the orifice in order toget reliable measurements and eliminate errors arising from turbulent flow. By theprovision of the inlet and outlet chambers in the device of the present invention, the turbulence of incoming and outgoingfiow is in effect insulated from the, orifice and absorbed therein so that long, straight runs on either side of the device are unnecessary. 'It will be clear to those skilled in the art that the apparatus of the present invention can also be used as a flow meter. By adjusting the orifice to provide a predetermined pressure differential with a given fluid, the flow across the orifice will be uniform under all conditions, I

In addition, it will be remembered that flow rate through an orifice is-proportional to the square root of the differences in pressure existingupstream and downstream from'the orifice. Flow rate meters are therefore essentially differential pressure gauges calibrated in gallons per minute. "Since the scale of the normal pressure gauge is uniform in pressure, flow rate ,is proportionate to the square root of the pressure'indications on the gauge with the result that flow rate scales are congested at the lower end and expanded at the higher end and the sensitivity of the device is correspondingly less at lower pressure differentials and greater as the pressure differential increases. By the use of the adjustable orifice of the preserit invention, the orifice size can be adjusted to meet the conditions of operation so that in effect, the optimum operating point on the pressure gauge scale can be shifted to any part of the scale simply by adjusting the orifice opening; Sensitivity will change correspondingly. Thus,

7 in effect, the orifice can be tuned to this metering circuit.

It will, of course, be clear that by providing various configurations for the orifice slot varying responses to pressure differential or flow can be obtained. Thus, for example, the orifice can be designed to give'what is known as a suppressed zero. As understood, this term refers to. an instrument constructed with the lower part of its range suppressed into a small portion of the total travel of'an indicator or scale but a relatively widely spread scale can be obtained over the upper portion of the scale. If such a scale is desired, the orifice may be of relatively large size at one end and small at the other end so that equal degrees of rotation of the cover or closure member produces unequal differences in total slot area. For example, if the slot over the first 20 degrees of opening is double the Width of that of the remaining 140 degrees, the scale calibration will be twice as great over the first 20 degrees as over the entire remaining 140 degrees and thus the accuracy of flow regulation is enhanced in the last portion.

Orifices may also be constructed with dual or triple ranges. This may be accomplished by having two or more slots in the orifice cylinder, circumferentially parallel, but displaced axially one from the other. The housing may then be constructed of sufiicient length so that the orifice adjusting sleeve may be positioned axially so as to unmask one, two, or more slots. Thus, there will be an orifice of double or triple range.

Other and further variations and adaptations of the invention herein disclosed to fit a variety of situations and conditions will be readily apparent to persons qualified in the art to which the invention pertains.-

1. In a differential pressure apparatus, means defining an adjustable orifice comprising: a cylindrical member having an axial flow passage opening through an end portion thereof, and an arcuate slot extending circumferentially approximately 160 about said cylindrical member and communicating inwardly with said flow passage; an assembly including a first annular member rotatable coaxially about said cylindrical member and having a planar transaxial end surface aligned with said slot, a second annular member rotatable coaxially about said cylindrical member and having a planar transaxial end surface juxtaposed to and confronting said first annular member end surface, an arcuate, fiat spacer betweensaid surfaces-extending icircumferentially approximately 200 and having an accurately predetermined axial width, and means retaining said annular member end surfaces in engagement with the'opposite surfaces of said spacer to define between said end surfaces an arcuate.

slitextending approximately from the opposite ends of the arcuate spacer in alignment with'said cylindrical member slot; and means for rotatably adjusting said assembly relative to said cylindrical member to vary the amount of circumferential alignment of said slit with said slot.

2. In a differential pressure apparatus, means defining an adjustable orifice comprising: a cylindrical member having a flow passage opening through an end portion thereof, and an arcuate slot extending circumferentially partially about said cylindrical member and communicating inwardly with said flow passage; an assembly including a first annular member rotatable coaxially about said cylindrical member and having a planar transaxial end surface, a second annular member rotatable coaxially about said cylindrical member, and having a planar transaxial end surface juxtaposed to and confronting said first annular member end surface, an arcuate, flat spacer between said surfaces and having an accurately predeten' mined axial width, and means retaining said annular member end surface in engagement with the opposite surfaces of said spacer to define between said end surfaces an arcuate slit having a circumferential extent approximately equal to the circumferential extent of said slot, and extending between the opposite ends of the arcuate spacer in alignment with said cylindrical member slot; and means for rotatably adjusting said assembly relative to said cylindrical member to vary the amount of circumferential alignment of said slit with said slot.

3. In a differential pressure apparatus, means defining an adjustable orifice comprising: a cylindrical member having a flow passage opening through a portion thereof, and an arcuate slot extending circumferentially partially about said cylindrical member and communicating inwardly with said flow passage; an assembly includinga first annular member rotatable coaxially about said cylindrical member and having a planar transaxial end surface, a second annular member rotatable coaxially about said cylindrical member and having a planar transaxial end surface juxtaposed to and confronting said first annular member end surface, an arcuate, flat-spacer between said surfaces and having an accurately predetermined axial width, and a screw extending through one annular member and said spacer, and threaded to the other annular member for retaining said annular member end surfaces in non-rotative engagement with the opposite surfaces of said spacer to define between said end surfaces an arcuate slit extending between the opposite ends of the arcuate spacer in alignment with said cylindrical member slot; and means for rotatably adjusting said assembly relative to said cylindrical member to vary the amount of circumferential alignment of said slit with said slot.

an adjustable orifice comprising: a cylindrical member having an axial, cylindrical recess opening through one end thereof, and an arcuate slot extending circumferentially about said cylindrical member and communicating inwardly with said recess adjacent the inner end thereof; an assembly including a first annular member rotatable coaxially about said cylindrical member andv having a planar transaxial end surface aligned with said slot, a second annular member rotatable icoaxially about said cylindrical member and having a planar transaxial end surface juxtaposed to and confronting said first annular member end surface, an arcuate, flat spacer between said surfaces and having an accurately predetermined axial width smaller than the axial width of the slot, and means retaining said annular member end surfaces in engagement 4. In a differential pressure apparatus, means defining with the opposite surfaces of said spacer to define between said second surfaces an arcuate slit extending between the opposite ends of the arcuate spacer in alignment with said cylindrical member slot; and means for rotatably adjusting said assembly relative to said cylindrical member to vary the amount of circumferential alignment of said slit with said slot.

5. The orifice means of claim 4 wherein the slot and slit have substantially equal circumferential extents about the axis of the recess.

References Cited in the file of this patent UNITED STATES PATENTS 1,043,935 Hitchcock Nov. 12, 1912 1,310,739 Cary July 22, 1919 2,158,737 Wunsch May 16, 1939 2,384,078 Curtis Sept. 4, 1945 2,951,501 Thylefors Sept. 6, 1960 

1. IN A DIFFERENTIAL PRESSURE APPARATUS, MEANS DEFINING AN ADJUSTABLE ORIFICE COMPRISING: A CYLINDRICAL MEMBER HAVING AN AXIAL FLOW PASSAGE OPENING THROUGH AN END PORTION THEREOF, AND AN ARCUATE SLOT EXTENDING CIRCUMFERENTIALLY APPROXIMATELY 160* ABOUT SAID CYLINDRICAL MEMBER AND COMMUNICATING INWARDLY WITH SAID FLOW PASSAGE; AN ASSEMBLY INCLUDING A FIRST ANNULAR MEMBER ROTATABLE COAXIALLY ABOUT SAID CYLINDRICAL MEMBER AND HAVING A PLANAR TRANSAXIAL END SURFACE ALIGNED WITH SAID SLOT, A SECOND ANNULAR MEMBER ROTATABLE COAXIALLY ABOUT SAID CYLINDRICAL MEMBER AND HAVING A PLANAR TRANSAXIAL END SURFACE JUXTAPOSED TO AND CONFRONTING SAID FIRST ANNULAR MEMBER END SURFACE, AN ARCUATE, FLAT SPACER BETWEEN SAID SURFACES EXTENDING CIRCUMFERENTIALLY APPROXIMATELY 200* AND HAVING AN ACCURATELY PREDETERMINED AXIAL WIDTH, AND MEANS RETAINING SAID ANNULAR MEMBER END SURFACES IN ENGAGEMENT WITH THE OPPOSITE SURFACES OF SAID SPACER TO DEFINE BETWEEN SAID END SURFACES AN ARCUATE SLIT EXTENDING APPROXIMATELY 160* FROM THE OPPOSITE ENDS OF THE ARCUATE SPACER IN ALIGNMENT WITH SAID CYLINDRICAL MEMBER SLOT; AND MEANS FOR ROTATABLY ADJUSTING SAID ASSEMBLY RELATIVE TO SAID CYLINDRICAL MEMBER TO VARY THE AMOUNT OF CIRCUMFERENTIAL ALIGNMENT OF SAID SLIT WITH SAID SLOT. 